Reverse conducting switching devices, such as IGFETs (insulated gate field effect transistors) and RC-IGBTs (reverse conducting insulated gate bipolar transistors) include an integrated body diode, which is forward biased under reverse bias of the switching device. A pn junction of the forward biased body diode injects charge carriers of both conductivity types that flood the semiconductor portion of the switching device and build up a dense charge carrier plasma that results in low electric resistance of the reverse biased switching device.
When the bias changes from reverse to forward, the body diode blocks and a reverse recovery current relieves the charge carrier plasma. The reverse recovery current contributes to dynamic switching losses of the switching device. In a desaturation period preceding a commutation following a change from reverse bias to forward bias, some transistor cells turn on such that injection of charge carriers along the pn junction of the body diode is reduced and the charge carrier plasma attenuates before commutation. A safety period between the end of the desaturation period and the start of commutation allows the switching device to timely restore its blocking capability with closed gated channels before commutation. During the safety period the charge carrier plasma may partially recover such that the safety period foils to some degree the effect of the desaturation period.
It is desirable to improve the switching characteristics of reverse conducting switching devices in electronic circuits.